Generally, a keyboard is a peripheral device for inputting characters or commands into an information apparatus such as a desktop computer, a notebook computer, a mobile phone or a tablet computer. FIG. 1 is a schematic top view illustrating the outer appearance of a conventional keyboard. As shown in FIG. 1, there are plural keys 10 on a surface of the conventional keyboard 1. When one of these keys 10 is depressed by the user's finger, a corresponding signal is issued to the information apparatus, and thus the information apparatus executes a function corresponding to the depressed key. For example, when the key 101 is depressed, a corresponding English letter or symbol is inputted into the information apparatus. When the key 102 is depressed, a corresponding number is inputted into the information apparatus. When the function key 103 is depressed, a corresponding function is quickly executed.
In case that the keyboard is used in a dim environment, the numbers and the characters marked on the keys of the keyboard are not clearly visible. In other words, the dim environment becomes hindrance from operating the keyboard. For solving these drawbacks, an illuminated keyboard has been introduced into the market.
Generally, after the conventional illuminated keyboard is manually turned on by the user, a light-emitting element is driven to emit a light beam. Moreover, after the conventional illuminated keyboard is manually turned off by the user, the light-emitting element stops emitting the light beam. As known, the way of manually controlling the illuminating function of the conventional illuminated keyboard is not user-friendly. Moreover, the illuminating function of the illuminated keyboard is usually enabled by the user in the dim environment. However, after the illuminated keyboard is used, the user often forgets disabling the illuminating function of the illuminated keyboard. Consequently, even if the illuminated keyboard is used in a bright environment or the illuminated keyboard is not used by any user, the light-emitting element still emits the light beam. In other words, the use of the conventional illuminated keyboard has the problem of wasting electric power.
For solving the above drawbacks, an illuminated keyboard with a proximity sensor is disclosed. FIG. 2 is a schematic cross-sectional view illustrating an illuminated keyboard with a proximity sensor. This illuminated keyboard 2 is disclosed in Chinese utility model patent Nos. CN201440241. As shown in FIG. 2, the illuminated keyboard 2 comprises a keycap layer 21, a light guide plate 22, a metal resilience layer 23, a membrane circuit board 24, at least one light emitting diode 25, an induction processing device 26, an induction antenna 27, and a keyboard housing 28. The induction processing device 26 is located at a side of an inner portion of the keyboard housing 28. The induction antenna 27 is electrically connected with the induction processing device 26.
When a user is located near the illuminated keyboard 2, the induction processing device 26 senses whether the user enters the sensing range according to the detecting result of the induction antenna 27. Consequently, the light emitting diode 25 is automatically turned on or turned off. In Chinese utility model patent Nos. CN201440241, the induction antenna 27 is directly printed on the membrane circuit board 24 or circularly disposed within the keyboard housing 28. In case that the induction antenna 27 is printed on the membrane circuit board 24, the induction antenna 27 should be separated from the traces of the membrane circuit board 24. Under this circumstance, the position of installing the induction antenna 27 is restricted. Whereas, in case that the induction antenna 27 is circularly disposed within the keyboard housing 28, the size of the keyboard housing 28 should be large enough to accommodate the induction antenna 27. Under this circumstance, the illuminated keyboard fails to meet the requirements of light weightiness, slimness and miniaturization. In the above two situations, since the induction antenna 27 is very close to the metal resilience layer 23, a signal interference problem occurs.
Therefore, there is a need of providing an improved illuminated keyboard with a proximity sensor in order to eliminate the above drawbacks.